The present applicant has previously proposed a fluorine-containing polymer comprising, as a polymerization unit, 5 to 100 wt. % of a polyfluoroalkyl alcohol(meth)acrylic acid derivative represented by the general formula:CnF2n+1(CH2CF2)a(CF2CF2)b(CH2CH2)cOCOCR═CH2   [I].An organic solvent solution or aqueous dispersion of this fluorine-containing copolymer can be effectively used as, for example, a surface modifier, such as a water- and oil-repellent or an oil barrier (see Patent Document 1).
Moreover, fluorine-based oils, such as perfluoropolyether oils, are increasingly used in combination with non-fluorine-based oils, such as hydrocarbon oils and silicone oils. However, since fluorine-based oils have a poor affinity for non-fluorine-based oils, which have been commonly used, it is very difficult at present to use them in combination.
It is also known that a polyfluoroalkyl(meth)acrylate copolymer is used as a film-forming component. For example, Patent Document 2 discloses a cosmetic comprising a copolymer of long-chain alkyl(meth)acrylate and fluorinated alkyl group-containing (meth)acrylate as a film-forming component. However, this copolymer has a softening point higher than room temperature, and film cracking and the like will occur under room temperature conditions.
Incidentally, it is reported that telomer compounds containing a perfluoroalkyl group having 8 to 12 carbon atoms are biologically degraded in the environment and converted to compounds having relatively high bioaccumulation and environmental concentration, causing concerns for exposure during treatment processes, and for release or diffusion from waste, treated substrates, etc., into the environment. Moreover, compounds containing a perfluoroalkyl group having 14 or more carbon atoms are very difficult to handle because of their physical and chemical properties. Hence, such compounds are rarely used in practice.
Furthermore, as for telomer compounds containing a perfluoroalkyl group having 8 or more carbon atoms (see Patent Documents 3 to 9), generation and incorporation of perfluorooctanoic acids with high bioaccumulation potential cannot be avoided in the production process of the telomer compounds. For these reasons, companies that produce such telomer compounds have retreated from the production of the compounds or promoted the use of alternative compounds containing a perfluoroalkyl group having 6 or less carbon atoms (see, for example, Patent Document 10).
However, compounds containing a perfluoroalkyl group having 6 or less carbon atoms cause a significant decrease in orientation on the surface of a treated substrate, and the melting point, glass transition point (Tg), etc., of the compounds are markedly lower than those of C8 compounds. Accordingly, the compounds are highly influenced by their environmental conditions, such as temperature, humidity, stress, and contact with organic solvents. Consequently, the desired performance cannot be sufficiently achieved, and durability and other properties are affected.